Just check & clean the carb slide and the inside of the carb venturi and airfilter hose - no need for expensive high-tech cleaning agents, just get the dust out of there...
With all the information you've given so far, I'm pretty sure that you shouldn't mess around with any other part of your carb until you've tried this...
Especially since you've been driving with an unclamped airfilter hose, I think there's just a few grains of sand in the airhose and venturi, which will keep the slide from sliding smoothly at random moments - and no fuel additive is going to help with that...